The present invention is directed to electronic control of engines. More specifically, the present invention is directed to a system and method for electronically controlling an engine including the ability to reprogram control variables without interrupting control operation.
Electronic control of engines for automotive and related applications is known. Most control schemes involve calculation of controllable variables in real time based upon prestored relationships and inputs from sensors that monitor engine operation. Most control schemes enable control variables to be calculated in both open-loop operation during engine warm-up when engine fluid temperatures necessitate a richer air/fuel ratio, and in closed-loop operation under normal operating conditions when feedback from an oxygen sensor in the engine exhaust is used to monitor the air/fuel ratio. These control schemes typically require time to calculate the control variables.
To reduce calculation time, look-up tables are used to obtain control parameters during engine operation. Initially, it was proposed to employ look-up tables in open-loop control during engine warm-up. A serious problem and limitation of such systems lies in the requirement that the tables be permanently stored in a programmable read-only memory or PROM that is initially programmed at the factory, and that requires removal and replacement to change or reprogram any of the stored control variables. Although such requirement for removal and replacement at a factory service facility or the like has been considered to be acceptable for normal passenger car and light truck applications in view of EPA requirements that critical engine control parameters not be variable outside of an authorized service environment, such schemes are unacceptable for racing and other off-road applications, and in development and test environments. In applications of these types, it is necessary that the control variables be readily, individually and selectively reprograrnnable by a technician or other operator at the site.
An engine control system that utilizes look-up tables stored in an EEPROM during both wann-up and normal operation was developed. An external programming unit enabled system memory to be reprogrammed without requiring removal of the memory package, to accommodate specific vehicle conditions, such as fuel quality, climate, etc. Nevertheless, control variables could not be adjusted during actual engine operation.
Subsequent developments have enabled control variables to be adjusted during engine operation. Nevertheless, those adjustments do not immediately take effect and control does not take place when adjustments are being made. Rather, when a user is making adjustments to a particular control variable, the control relationship using the particular control variable is temporarily disabled. This leads to loss of responsiveness in the control process and to a potential dangerous situation.
It is an object of the present invention to overcome these and other drawbacks with conventional engine control systems.
It is another object of the present invention to provide a system and method for electronic control of engine operation that enables real-time reprogrammability of engine control relationships without disabling control functionality.
It is another object of the present invention to provide a system and method for electronic control of engine operation that enables reprogramming of engine control relationships and the control algorithm.
Another object of the invention is to provide a method and system for electronic engine control in which the engine control variables may be readily and selectively varied in real time without disabling control functionality, so that the operator may readily observe the effects of parameter variation and make any desired further adjustments without necessitating removal of table memory or other electronic circuitry.
Another object of the present invention is to provide a system and method for electronic engine control in which control variable tables are displayed to an operator to facilitate selective variation of the control relationships.
According to one embodiment, an engine control system for providing electronic control signals to an engine is disclosed. The system comprises one or more sensors that produce input signals in response to engine operating conditions and one or more control apparatus, responsive to the electronic control signals, that control engine operating conditions. An electronic control unit produces the electronic control signals in response to the input signals based on a set of defined relationships and a-user controller enables viewing and modifying of the set of defined relationships. The electronic control unit comprises a unique memory structure that enables selective rewriting of the set of defined relationships in real-time without interrupting control operation by the user controller.
According to another embodiment, a method of controlling an engine is disclosed. The method comprises providing one or more input signals in response to engine operating conditions and producing electronic control signals in response to the input signals based on a set of defined relationships. The electronic control signals are used by one or more control apparatus that control engine operating conditions. The defined relationships may be selectively modified in real-time without interrupting the production of electronic control signals.
Other features and advantages of the present invention will be apparent to one of ordinary skill in the art upon reviewing the detailed description of the present invention.